Abstract

Fast pyrolysis bio-oil has unfavorable properties that
restrict its use in many applications. Among the main
issues are high acidity, instability, and water and
oxygen content, which give rise to corrosiveness,
polymerization during storage, and a low heating value.
Esterification and azeotropic water removal can improve
all of these properties. In this work, low acidity
bio-oils were produced from fast pyrolysis bio-oil via
esterification with methanol or n-butanol. Esterification
conversion was enhanced by azeotropic water removal prior
to and/or during esterification. An additional
hydrocarbon entrainer (n-heptane or petroleum ether) was
required for efficient water removal. The product oils
had total acid numbers ranging from 5 to 10 mg KOH/g and
pH values from 4.0 to 5.6. The best results were obtained
with 1:0.9:0.1 wt ratio of bio-oil, n-butanol, and
n-heptane and p-toluenesulfonic acid (p-TSA) as catalyst.
Removal of homogeneous catalyst (2 wt % p-toluenesulfonic
acid (p-TSA)) was attempted by precipitation,
centrifugation, and water washing, but only 41-82 wt % of
the catalyst could be recovered from the product oil
based on sulfur content. Solid acid catalysts were more
efficient with methanol than n-butanol in dry conditions.
An organic base (triethylamine) was tested for
neutralizing the methanol esterified bio-oil's residual
acidity. Nitrogen content increased by 0.1-0.4 wt % when
pH values of 6-8 were obtained.

title = "Upgrading fast pyrolysis bio-oil quality by esterification and azeotrop water removal",

abstract = "Fast pyrolysis bio-oil has unfavorable properties that restrict its use in many applications. Among the main issues are high acidity, instability, and water and oxygen content, which give rise to corrosiveness, polymerization during storage, and a low heating value. Esterification and azeotropic water removal can improve all of these properties. In this work, low acidity bio-oils were produced from fast pyrolysis bio-oil via esterification with methanol or n-butanol. Esterification conversion was enhanced by azeotropic water removal prior to and/or during esterification. An additional hydrocarbon entrainer (n-heptane or petroleum ether) was required for efficient water removal. The product oils had total acid numbers ranging from 5 to 10 mg KOH/g and pH values from 4.0 to 5.6. The best results were obtained with 1:0.9:0.1 wt ratio of bio-oil, n-butanol, and n-heptane and p-toluenesulfonic acid (p-TSA) as catalyst. Removal of homogeneous catalyst (2 wt % p-toluenesulfonic acid (p-TSA)) was attempted by precipitation, centrifugation, and water washing, but only 41-82 wt % of the catalyst could be recovered from the product oil based on sulfur content. Solid acid catalysts were more efficient with methanol than n-butanol in dry conditions. An organic base (triethylamine) was tested for neutralizing the methanol esterified bio-oil's residual acidity. Nitrogen content increased by 0.1-0.4 wt % when pH values of 6-8 were obtained.",

N2 - Fast pyrolysis bio-oil has unfavorable properties that
restrict its use in many applications. Among the main
issues are high acidity, instability, and water and
oxygen content, which give rise to corrosiveness,
polymerization during storage, and a low heating value.
Esterification and azeotropic water removal can improve
all of these properties. In this work, low acidity
bio-oils were produced from fast pyrolysis bio-oil via
esterification with methanol or n-butanol. Esterification
conversion was enhanced by azeotropic water removal prior
to and/or during esterification. An additional
hydrocarbon entrainer (n-heptane or petroleum ether) was
required for efficient water removal. The product oils
had total acid numbers ranging from 5 to 10 mg KOH/g and
pH values from 4.0 to 5.6. The best results were obtained
with 1:0.9:0.1 wt ratio of bio-oil, n-butanol, and
n-heptane and p-toluenesulfonic acid (p-TSA) as catalyst.
Removal of homogeneous catalyst (2 wt % p-toluenesulfonic
acid (p-TSA)) was attempted by precipitation,
centrifugation, and water washing, but only 41-82 wt % of
the catalyst could be recovered from the product oil
based on sulfur content. Solid acid catalysts were more
efficient with methanol than n-butanol in dry conditions.
An organic base (triethylamine) was tested for
neutralizing the methanol esterified bio-oil's residual
acidity. Nitrogen content increased by 0.1-0.4 wt % when
pH values of 6-8 were obtained.

AB - Fast pyrolysis bio-oil has unfavorable properties that
restrict its use in many applications. Among the main
issues are high acidity, instability, and water and
oxygen content, which give rise to corrosiveness,
polymerization during storage, and a low heating value.
Esterification and azeotropic water removal can improve
all of these properties. In this work, low acidity
bio-oils were produced from fast pyrolysis bio-oil via
esterification with methanol or n-butanol. Esterification
conversion was enhanced by azeotropic water removal prior
to and/or during esterification. An additional
hydrocarbon entrainer (n-heptane or petroleum ether) was
required for efficient water removal. The product oils
had total acid numbers ranging from 5 to 10 mg KOH/g and
pH values from 4.0 to 5.6. The best results were obtained
with 1:0.9:0.1 wt ratio of bio-oil, n-butanol, and
n-heptane and p-toluenesulfonic acid (p-TSA) as catalyst.
Removal of homogeneous catalyst (2 wt % p-toluenesulfonic
acid (p-TSA)) was attempted by precipitation,
centrifugation, and water washing, but only 41-82 wt % of
the catalyst could be recovered from the product oil
based on sulfur content. Solid acid catalysts were more
efficient with methanol than n-butanol in dry conditions.
An organic base (triethylamine) was tested for
neutralizing the methanol esterified bio-oil's residual
acidity. Nitrogen content increased by 0.1-0.4 wt % when
pH values of 6-8 were obtained.